You need not think the earth-worms did that. Not at all! The earth-worms never behave so ill. The “worms” that people mean, when they speak of this harm done, are the grubs or larvæ of some insects, as of the daddy-long-legs and others.
These grubs and cut-worms will eat living plants, but Mr. Worm likes dead leaves and stems best. He wants his food made soft by decay.
Now we come to the chief work of the true earth-worms. When they make their halls and houses, they fill their long bodies with the earth. Some say it is their food.
Mr. Darwin says, “Oh, no! they fill their bodies with earth just to get it out of their way.” If they get any food from the dirt it is not much. They turn themselves into baskets to carry the dirt out from their houses.
The worms work, work, work all the time, taking out earth, and carrying it to the top of the ground.
There they pile it in heaps, called worm-casts. Each piece is the shape of a small worm.
The earth takes this shape as the worm presses it out of its long, soft body. Early in the day you can find these worm-casts over all the garden paths. So you can after a rain. Go and look for them.
There are so many worms busy all the time that each year they bring up tons of earth. This shows you the power that is in small, weak things. In India there are worm-casts in heaps six inches high.
The worms make the earth fine and loose, by pinching it off with their mouths. Then they bring this rich soil from below, and lay it on top, and so on and on.
It is only some twenty years since this work of worms was known. At first people said, “Oh, no, no! It cannot be that little, soft worms could cover a great field, some inches deep, with new earth.” But it was shown to be quite true.